1. Field of the Invention
The present invention is directed to conveyor belts, and in particular, to modular conveyor belts. The present invention is further directed to methods for assembling such belts.
2. Description of Related Art
Conveyor systems are commonly used in various industrial fields for material handling and processing purposes. For instance, conveyor systems are used in food processing systems in which food items are placed on the support surface of a conveyor belt and are processed while being conveyed from one location to another. In such applications, the food items may be cooked, baked, frozen, washed, or subject to other processing steps while being conveyed on the conveyor belt. Various different types of conveyor belts have been used in such applications such as wire mesh conveyor belts but various modular belts have become especially popular in food processing systems. Moreover, such conveyor systems are often used in a helical accumulator such as that disclosed in U.S. Pat. No. 5,070,999 to Layne et al. which allows storage of a large number of items in the conveyor system.
Many modular conveyor belts include a plurality of link elements, each link element having a plurality of spaced intermeshing extensions that intermesh with extensions of adjacent link elements. The intermeshed link elements are hingeably interconnected together by elongated pivot rods so as to form a continuous conveyor belt, the plurality of link elements providing the conveying surface. The link elements are generally made of a non-metallic material such as plastic, nylon, or other composite materials. The use of such link elements has become popular especially in food processing applications because the conveyance surfaces are easy to clean and can be treated to resist growth of pathogens such as germs, fungus, viruses and bacteria. In such a manner, modular conveyor belts can aid in the reduction of food borne ailments by improving sanitation.
Various conveyor belts are also known in which pivot rods are inserted into intermeshed link elements, the rods being retained by a feature provided on the link elements. For example, U.S. Pat. No. 5,105,938 to Tan discloses a conveyor belt having links that are interdigitated and pivotably connected by rods, a belt link end being provided on the links that have an aperture with an occlusion to retain the pivot rod in place at one of two bi-stable positions. The patent to Tan discloses a substantially round exit-entrance aperture to allow installation and/or removal of the pivot rod, and a ridge or waist resiliently formed for holding the pivot rod. However, this patent requires the rods to be moved over the ridge via deformation of the ridge which can weaken the links depending on the material from which the links are made. Moreover, inadvertent removal of the rods can occur if the rod is unintentionally moved to a position in which the pivot rod aligns with the exit-entrance aperture.
U.S. Pat. No. 5,598,916 to Horton et al. discloses a modular conveyor belt similar to that disclosed above with respect to Tan, except that the modular conveyor belt links of this reference does not include a ridge. The aperture provided on the belt links allows installation and removal of the rod. However, in this patent, the aperture is offset relative to rod receiving aperture of the links thereby requiring the insertion of the pivot rods at an angle, or alternatively, the use of a bendable pivot rod. The insertion of the pivot rods at an angle is cumbersome and may often be difficult to achieve whereas use of a bendable pivot rod is not desirable in many applications due to reduced strength.
In addition, various other modular conveyor belts have been proposed that provide other integral features, especially at the side edges of the conveyor belt. For example, U.S. Pat. No. 6,523,680 to Guldenfels discloses a modular conveyor belt including edge link ends at the outer periphery of the link elements that nest with other link ends when the conveyor belt is collapsed. U.S. Pat. No. 5,372,248 also to Horton discloses a radius conveyor belt having link elements with projections extending from the edge surface thereof which engage support flanges of side rails to support the conveyor belt during operation. Such support flanges can prevent tenting of the conveyor belt. However, providing side rails for the length of the conveyor belt is cost prohibitive. Moreover, U.S. Pat. No. 6,644,466 to Knott et al. discloses a platform top radius belt in which the modules include protrusions that extend to support an end of the pivot rod, the protrusion fitting between a projecting portion and a narrow hinge element. This patent discloses that the protrusion includes a notch so as to allow the pivot rod to be inserted into the apertures of the hinge elements but does not prevent unintentional removal of the rod.
The above described conveyor belts provide solutions to a variety of different conveyor belt issues such as installation and retention of pivot rods. However, the conveyor belts do not provide an integrated solution to these issues associated with use of conveyor belts. Therefore, there still exists an unfulfilled need for a conveyor belt that provides an integrated solution to such issues. In particular, there still exists an unfulfilled need for a conveyor belt that allows easy installation and retention of pivot rods. In addition, there still exists an unfulfilled need for a conveyor belt that reduces the likelihood of tenting, and provides a mechanism to control the minimum turn radius of a conveyor belt.